The invention relates to a method and a device for fracture-splitting a workpiece comprising one or more ring-shaped workpiece sections axially aligned in sequence.
Known from DE 197 04 131 A1 is a method for fracture-splitting a workpiece comprising one or more ring-shaped workpiece sections axially aligned in sequence, the method comprising the following steps: firstly, producing two diametrally opposed fracture notches each in the bores by the ring-shaped workpiece sections, this usually being done in a machining station provided specially for this purpose. After the fracture notches have been produced, the workpiece is removed from the machining station, transferred to a special clamping and supporting fixture where it is located for the actual fracture-splitting step. Between removal and location, the workpiece may be or must be buffered for a certain time before an expander means is introduced axially into the bores formed by the ring-shaped workpiece sections and expanded to fracture-split at least one ring-shaped workpiece section. The device as disclosed in DE 197 04 131 A1 for implementing the method comprises a clamping and supporting fixture for locating the workpiece and an expander means for insertion into and expanding axially the bores formed by the ring-shaped workpiece sections.
A comparable method and a comparable device are each disclosed furthermore in WO 95/28248, EP 0 167 320 B1 and U.S. Pat. No. 4,684,267.
The invention is based on the technical objective of providing a method for fracture-splitting a workpiece as well as a device for fracture-splitting a workpiece suitable for such a method with which machining the workpiece is further rationalized by ways and means as simply and effectively as possible whilst enabling the technical complications in production of the device to be reduced.
The technical objective as cited above is achieved by a method in accordance with the invention having the features as set forth in claim 1.
This method for fracture-splitting a workpiece comprising one or more ring-shaped workpiece sections axially aligned in sequence comprises the following steps: locating the workpiece for fracture-splitting; axially inserting at least one expander means into at least one bore formed by each ring-shaped workpiece section; producing at least one fracture notch in at least one bore during and/or after axial insertion of the expander means; and expanding the expander means to fracture-split at least one ring-shaped workpiece section.
Producing the fracture notch is done preferably with a parting means as detailed in the following in conjunction with the description of the device in accordance with the invention. Producing the fracture notch in this arrangement may be implemented both from only one and from both axial sides of the bore formed by each ring-shaped workpiece section. When two expander means are used in the method in accordance with the invention, it is in addition likewise possible to insert the expander means from two opposite axial sides into one or more bores formed by each ring-shaped workpiece section.
With the method in accordance with the invention the at least one fracture notch can be produced directly at the workpiece already located in preparation for the fracture-splitting during and/or (directly) after insertion of the expander means but still prior to the actual fracture-splitting action. Preferably, the fracture notch is finish-machined either during or after insertion of the expander means, although it is just as conceivable to configure during insertion only part of the fracture notch and to produce the other part once the expander means has been inserted partly or fully.
The additional step in producing the at least one fracture notch to be implemented in advance and making available a machining station solely provided for this purpose, as required in prior art, can be eliminated in the method in accordance with the invention in thus also eliminating the steps of removing the workpiece from the cited machining station and transferring and reclamping the workpiece in the clamping and supporting fixture used for fracture-splitting. This also does away with the need for any external buffering of the workpiece in the time between producing the fracture notch and actual fracture-splitting.
Machining the workpiece up to and including the fracture-splitting procedure can now be considerably accelerated and simplified. The method in accordance with the invention permits by relatively simple and effective ways and means considerably rationalizing machining the workpiece whilst reducing the technical complications in producing the device. The method in accordance with the invention is applicable, for example, for both
a) single workpiece having a single ring-shaped workpiece section,
b) an axially aligned sequence of several single workpieces having a single ring-shaped workpiece section,
c) one or more workpieces having several ring-shaped workpiece sections axially aligned in sequence, and
d) for combinations of a)-c).
Further advantageous aspects of the method in accordance with the invention read from the corresponding sub-claims 2 to 9.
The objective forming the basis of the invention is furthermore achieved by a device in accordance with the invention having the features of claim 10.
This device for fracture-splitting a workpiece including one or more ring-shaped workpiece sections axially aligned in sequence comprises: at least one clamping and supporting fixture for locating the workpiece for fracture-splitting; at least one expander means for axial insertion into at least one bore formed by each ring-shaped workpiece section and expansion thereof; and at least one parting means arranged substantially at the circumference of the expander means and slaved in the movement thereof axially for producing at least one fracture notch in at least one bore during and/or after axial insertion of the expander means.
The parting means (which as regards its function in producing the fracture notch is not to be confused with the means provided for actual fracture-splitting of the workpiece) is preferably a parting means having at least one geometrically defined cutting edge, although it is understood that the invention is not restricted exclusively to this type of parting means. Just as well, the parting means may comprise geometrically non-defined cutting edges (e.g. as a grinding tool) or even configured as a parting means in which the parting action functions on the basis of thermal, chemical or electrochemical material removal, for example, in the scope of a spark erosion means or a laser cutting means and the like, whereby combinations of the individual parting means types are likewise conceivable.
In this arrangement, the parting effect of the parting means needed to produce at least one fracture notch is achievable during insertion of the expander means on which the parting means is arranged, for example by a relative movement between the parting means and the bore, on which the fracture notch is to be produced, produced due to the axially insertion movement or by a combined relative movement between the parting means, expander means and workpiece. In producing the fracture notch after insertion of the expander means, however, the position of the expander means relative to the bore remains preferably constant and merely a relative movement between the parting means and the corresponding workpiece surface and/or the stationary expander means is implemented. However, in both cases, advancing the parting means relative to the workpiece surface of the bore may involve components extending not only substantially parallel to the axial insertion direction but also at an angle thereto.
Since the parting means, as aforementioned, is arranged on the expander means, the expander means may expediently serve as a means of driving and/or advancing the parting means, although it is just as possible in the sense of the invention that the parting means is driven and/or advanced independently of the expander means.
The device in accordance with the invention offers the advantages as already detailed at the outset in conjunction with the method in accordance with the invention. By arranging the parting means on the expander means, the expander means has in addition an advantageous dual function by it functioning to a certain extent as a functional component of the parting means whilst taking over in conjunction therewith the additional function of an otherwise separately needed machining station for producing the fracture notch. Accordingly, the device in accordance with the invention is thus provided with a kind of combined fracture notching/splitting tool.
Further advantageous aspects of the device in accordance with the invention read from the corresponding sub-claims 11 to 19.
Preferred example embodiments of the invention including additional aspects and further advantages thereof will now be detailed with reference to the attached drawings.